The invention relates to acid-neutralizing filter media for a liquid filter in a liquid filtration system, including diesel lubricant filters.
The invention arose during continuing development efforts directed toward diesel lubricant filters removing combustion acids in the lube oil circulated by the diesel engine lubricant circulation system, though the invention has broader application. It is known in the prior art to provide a filter with a strong base for reacting with lubricant containing combustion acids neutralized by a weak base to a neutral salt in the engine lubricant circulation system, for example as noted in U.S. Pat. No. 4,906,389, incorporated herein by reference. In the prior art, combustion acids are neutralized by a weak base in the oil. The neutralized acid is transported to a filter containing a strong base where the acid exchanges weak base in solution for strong base on the filter and forms an insoluble, neutralized, immobile salt deposit that is retained on the filter. The replaced weak base returns to the circulation system for re-use to neutralize further combustion acids, for example at the piston ring zone. The cycle then continues, namely the weak base neutralizes the combustion acids to form neutral salts which are transported from the piston ring zone with the lubricating oil and circulated through the lubricant circulation system including the filter, whereat the strong base replaces the weak base and retains the combustion acids as immobilized deposits on the filter media.
The present invention developed from continuing efforts to improve attachment of the strong base to the filter media.